Probably the only musical instrument prior to the present invention in which the size and shape of the mouth is used to modulate the tone of the instrument is a Jew's harp. The basic design of a Jew's harp has been disclosed in prior U.S. patents, including U.S. Pat. No. 4,161,902 to Siverson. The tone which the mouth modulates is produced by a metal tongue which is struck by the fingers of the user. Another prior art device which uses the mouth of the user as a sounding box is disclosed in U.S. Pat. No. 527,675 to Enriquez. This musical instrument is played by picking the playing strings with the fingers, much like a guitar is played. The mouth of the user is placed against the back of the head of the instrument. As the fingers of one hand strum the strings, the fingers of the other hand are moved along the instrument pressing the strings against the proper frets to execute a tune on the strings. With the proper distension and contraction of the cheeks and movement of the lips of the performer together with a vibration of his tongue, an aeolian harmony to the sounds produced by the instrument is obtained.
In most stringed musical instruments, such as the common guitar and violin, a sound box located at one end of the instrument is used to project the various tones produced by the strings. However, other means of projecting sound have been disclosed in the prior art. For example, in U.S. Design Pat. No. 70,509 to Peroutek, a horn-like device is attached to one end of a stringed instrument to project the sound. In the device disclosed in U.S. Pat. No. 2,033,826 to Haium, a sound box is disclosed which is placed against the strings to project the sound.
A variety of shapes or designs of stringed musical instruments have also been disclosed in the prior art. For example, in U.S. Design Pat. No. 158,469 to Kohn, a violin having a bowed neck portion is disclosed. In order to increase the resonance for better tone quality in a stringed instrument, a second set of strings has been included in the musical instrument. For example, in U.S. Pat. No. 685,920 to Heck, a spring resonance device is located in the body of the stringed instrument. In U.S. Pat. No. 586,032 to Hartman, a second set of strings located along the length of the instrument is disclosed. An adjustable neck brace for a musical instrument which is used to counteract the warping caused by the strings is disclosed in U.S. Pat. No. 4,167,133 to Adams, Jr.
As shown by the prior patents cited above, there has been a constant striving in the art to produce stringed musical instruments having new and improved tone quality.